To treat cardiac arrhythmia for example diseased areas of the heart are eradicated by means of catheter ablation in an electrophysiological intervention. In this process one or more catheters are first inserted into the relevant ventricle for electrophysiological mapping of the cardiac wall. When the diseased area has been located, it is eradicated using an ablation catheter with a heat-generating high-frequency current. It is possible to treat cardiac arrhythmia permanently in this manner.
Electro-anatomical mapping systems, such as the Carto-System from Biosense Webster, Diamondbar, Calif., USA, are used in this process to visualize the ablation catheter during the ablation procedure in a representation of the cardiac anatomy. The Carto-System includes a position sensor contained in the ablation catheter and a location device positioned below the patient. This comprises three transmitters of electromagnetic radiation, which is picked up by the position sensor and allows said position sensor to be located to an accuracy of up to 1 mm.
There is however the risk with ablation that adjacent tissue areas may be irreparably damaged. When treating atrial fibrillation, ablation at the posterior wall of the left atrium can for example cause perforation in the esophagus, if the ablation is carried out in the vicinity of the esophagus, which is adjacent to the epicardium. Ablation in the vicinity of the pulmonary veins that open into the left atrium can also cause stenosis of the pulmonary veins.
There is therefore cause to insert a temperature probe into the esophagus, to monitor the temperature in the esophagus during the ablation procedure. If the temperature increases, the ablation could be stopped or the power output of the ablation catheter could be reduced, to prevent damage to the esophagus. However there are as yet no temperature probes, which are ideally suited for such an application.
A temperature probe for insertion into a body lumen, in particular a blood vessel, is known from US 2004/0147852 A1. This has a balloon catheter, on the outside of which temperature sensors can be disposed. When the balloon is inflated, the temperature sensors are pushed onto the inside of the blood vessel and can therefore measure the temperature at the vessel wall very accurately. This is used to identify inflammatory plaque. The balloon catheter is also provided with x-ray visible markers for better visibility in the x-ray image.
US 2002/0115991 A1 describes a device for thermal treatment of the esophagus, in particular the mouth of the esophagus. The heat-emitting elements, for example electrodes, are disposed on the outer skin of an inflatable balloon element, to be brought into direct contact with the sphincter muscle to be treated. The balloon element can be deflected by a cable. Temperature sensors can also be disposed on the balloon element in addition to the electrodes. Parts of the device are optionally configured to be x-ray visible, so that said device is visible on fluoroscopy images and the intervention can be effectively controlled as a result.
WO 00/27278 describes a further thermosensor for insertion into blood vessels, wherein temperature sensors are disposed on the outside of an inflatable balloon element.
A thermosensor for the rectum is known from U.S. Pat. No. 6,348,039, which similarly has an inflatable balloon element, to the outside of which at least one temperature sensor is attached. This is used during hyperthermia treatment of prostate cancer to control temperature changes in the prostate.
EP 0 485 323 A1 similarly discloses the use of a temperature probe during hyperthermia treatment of the prostate. A heat applicator is inserted into the rectum and a catheter with the temperature probe is inserted into the urethra. The catheter contains a balloon, which is inflated in the bladder, to fix the position of the catheter end in relation to the prostate. Means for measuring the distance between the heat applicator and the temperature probe are similarly provided.
WO 97/41924 describes a catheter for hyperthermia treatment of the womb. This comprises a balloon catheter, to the outer skin of which both antennas for electromagnetic radiation and also temperature sensors are attached. After insertion into the womb, the balloon is inflated, such that the antennas and temperature sensors are pushed onto the inner wall of the uterus.